When I Try To Log On A Server My Minecraft Crashes! JEB HELP ME PLZ

Put the summary of the bug you're having here

What I expected to happen was...:
I would have been able to get on a prision server so I can do my job as a guard

What actually happened was...:
I couldn't because every thine I try my Minecraft Crashes

Steps to Reproduce:
1. I get on my account and play in 1.7.10
2. I get on Cryptic facility prision server where I am a guard
3.and then it says logging on and then I crash
I hope thats what u mean by reproduce _